Noise in the Presence of Coupling Among Antenna Elements

Noise temperature calculation and minimum noise temperature design of feed structures for large scale antenna arrays is given in Demir et al. (1)-(3). In those studies the portion of internally generated noise power appearing at the antenna element terminals was not calculated because the feed system is assumed to be matched to the antenna elements and therefore reflections do not occur and all the noise power dissipates on or radiates through the antenna elements. However, even in the matched case, some part of the noise power may return back to the output port if there is coupling among antenna elements. In this study, it is assumed that internal noise power at the antenna element terminals is coupled to the neighboring antenna elements and received as noise power input. This consideration has two aspects: the noise power at the output terminal is changed and noise signals at the output terminal are not any more uncorrelated and therefore requires a special treatment.